Carisbrooke Castle is a historic motte-and-bailey castle located in the village of Carisbrooke near Newport. The site may have been occupied in pre-Roman times. The existence of a ruined wall suggests that there was a building there in late Roman times. The Jutes may have taken over the fort by the late 7th century. An Anglo-Saxon stronghold occupied the site during the 8th century. Around 1000, a wall was built around the hill as a defence against Viking raids.

From 1100 The castle remained in the possession of Richard de Redvers' family, and over the next two hundred years his descendants improved the castle with stone walls, towers and a keep. This was until 1293, when Countess Isabella de Fortibus, the last Redvers resident sold it to Edward I, after which the government was entrusted to wardens as representatives of the crown. In the reign of Richard II it was unsuccessfully attacked by the French. The keep was added to the castle in the reign of Henry I, and in the reign of Elizabeth I; when the Spanish Armada was expected, it was surrounded by an elaborate pentagonal fortification by Sir George Carey.

A model of Carisbooke Castle as it appeared during the 14th century

Carisbrooke was the strongest castle on the Island; though it is visible from some distance, it does not dominate the countryside like many other castles.

There are traces of a Roman fort underneath the later buildings. Seventy-one steps lead up to the keep; the reward is a fine view. In the centre of the castle enclosure are the domestic buildings; these are mostly of the 13th century, with upper parts of the 16th century. Some are in ruins, but the main rooms were used as the official residence of the Governor of the Isle of Wight until the 1940s, and they remain in good repair.

The Great Hall, Great Chamber and several smaller rooms are open to the public, and an upper room houses the Isle of Wight Museum. Most rooms are partly furnished, but on the whole it is the fireplaces and other features of the rooms themselves which generate the most interest. The gateway tower was erected by Lord Scales who was lord of the castle at the time in 1464.

The chapel is located next to the main gate. Within the walls is a well 200 feet deep and another in the centre of the keep is reputed to have been still deeper. Near the domestic buildings is the well-house with a donkey wheel.

Surrounding the whole castle are large earthworks, designed by the Italian Federigo Gianibelli, and begun in the year before the Spanish Armada. They were finished in the 1590s. The outer gate has the date 1598 and the arms of Queen Elizabeth I.

Norris Castle stands on the northeast point of East Cowes. The castle was designed by James Wyatt for Lord Henry Seymour. It has a galleted facade with crenellations, but all of this is for show as the castle has no defensive fortifications. The building's original function was entertaining. Despite its size, it has only four bedrooms. The illusion of size is created by the fact that most of the building is occupied by only one room.

Yarmouth Castle is a small off-square blockhouse built by Henry VIII in 1547, to guard Yarmouth harbour. It was built as part of Henry's programme to fortify the English coast with a chain of coastal defences known as Device Forts or Henrician Castles. These were built to guard against the threat of foreign invasion. As it is a later fortification it did not have the earlier rounded or concentric shape but a square keep with angular bastions.

The Isle of Wight was a target of attempted French invasions, and there were notable incursions. Henrician Castles were built in both settlements in the sixteenth century. The west fort in Cowes still survives to this day, albeit without the original Tudor towers, as West Cowes Castle. The fort built in East Cowes is believed to have been similar but was abandoned c1546 and since destroyed.